Summary

The Decagram is basically an attempt to take the canon of Tokyo Babylon and X/1999 as it was given up to X/1999 vol. 18.5 and return it subsequently to the principle of yin and yang rather than the Christian fatalism prevalent in the later books of X.

The focus is firmly on Sakurazuka Seishiro and Sumeragi Subaru, their involvement in bringing these changes to pass, and the resulting relationship between them. However, other canon characters and the history of the clans of Sumeragi and Sakurazuka are explored as well.